Avoidance can take many forms in the context of PTSD, including avoiding memories, thoughts or feelings related to the trauma, as well as people, places and objects.
Avoidance in the context of PTSD serves to protect you from remembering or reliving distressing traumatic reminders.
Avoidance can get in the way of your daily life and goals. In addition to PTSD, it's also a common symptom of anxiety disorders and obsessive-compulsive disorder (OCD).